Is there a formula for powders slower than listed in the manual??

[JustC]

I have been long wanting to know how to figure out how to determine load data for powders slower than those listed in the manual. Let's say I have a wildcat,..oh let's say a 6.5-06imp with a 1:8 twist tube. If I want to speed her up with a slower powder (the listed powders just don't do the 140gr pills any justice),..what do I calculate to find a charge range in the slower powders to be sure I don't blow the action up because of a secondary ignition effect?

Thanks for any help.

 

[4mesh063]

I've never used a formula per-se, but I have made guesses on loads and tried to be in the safe area for it. As an example, if the gun I have shoots 60gr of 4831 and that's at the upper end but without pressure. Well, 60 of H1000 will be plenty safe, if it fits. Then after seeing 1 round over a chronograph, I move up in charge if I have determined that it isn't causing any trouble. Going slower in burn rate is fine with me. Going faster is NOT fine and can lead to catastrophic failures. Dont go faster on the burn chart without hard data from a RECENT reloading manual for the round you are shooting. If there is no data on a faster powder, theres a VERY GOOD REASON why not. Also, don't go several steps on the burn rate chart at one time. Use only powders you are familiar with and have an idea of what to expect from.

I'd highly doubt that a slower powder will help your 06imp anyhow. H1000 or R25 would be about as slow as I could see working. Slower stuff than that is simply for filling super overbore cases. H870 or WC872 is gonna be way full and won't give any more velocity than 4831sc. Retumbo is gonna be about the same. MRPII is WAY slow/Volume too.

 

[Mikecr]

Toss the manuals in the nearest dumpster and purchase QuickLoad. You won't be sorry.

 

[4mesh063]

Justin,

For H1K or R25 Just add about 4% to 6% onto the loads you have for H4831SC and you'll be in the ball park. You will probably be able to move up from there but try it first. One shot at a time.

These extruded powders are not much different than the parent powders. (They are actually the very same powder with different extrusion sizes, or, in the case of R25, A different coating). In any case, going slower with these 2 you'll be fine if you're using R22 or H4831SC as a guide. Don't even bother with Retumbo or MRP II then because you'll see a marked dropoff in velocity. I think the Retumbo could be nice stuff if you have a case big enough but for an 06, forget it.

 

[Warren Barrett]

JustC, if you haven`t already tried IMR7828, then it may be worth a try. It does very well in my 6.5 Gibbs( 6.5-06 imp.)with 26 inch barrel as far as accuracy and velocity is concerned with 140 gr. class bullets.

 

[dwm]

4mesh063, Retumbo shoots great in my 25-06, I see no reason it wouldn't shoot in his 6.5-06 Imp. I can get ~3150 fps with a 115 Nosler BT using 60 grains of Retumbo, 26" barrel. Nice little .3 to .5 MOA 5 shot groups too.

I was under the impression that RL25 burn rate was almost the same as Retumbo, slower than H1000.

Hodgdon puts out an Annual Manual that has load data for the 6.5-06 in it. Bought the manual from MidwayUSA for next to nothing. Has a lot of data in it.

Manual lists H1000/142 gr Sierra HPBT starts at 49 gr and goes up to 55 compressed, maxes out at ~2816 fps with a 24" barrel. With the improved case he should be able to do a bit better than this ....

 

[Brent]

Doug,
Retumbo is 4-5gr slower than RL25 in the 300 Ultra and 30-338 Lapua FWIW. Worth an extra 50-100 fps it seems.

 

[JustC]

thanks guys.

4mesh063,.it is H1000 and RL25 that I am in search of data for. I have nothing for these 2 powders in either the nosler or sierra manual. Not to mention there is no data in them for the IMP version of this chambering. Just looking for good accuracy at a higher velocity.

I will be checking into quickload,..I think I have put it off long enough.

 

[H-BAR]

Why not pose the question to the manufacturer of what powders you seek to use.
I have gotten good responses from Alliant about their powders when ever I had a question. These guys work with their powders so much they know the ins and outs with each powder.

 

[JustC]

I hadn't considered that H-BAR. I may just give them a call and ask if THEY have some sort of formula they use for testing.

Thanks for the info guys,..I will be trying the RL25, Retumbo, 7828 and H1000 to see how fast I can push these 140's and still maintain sub .5moa groups. I'll post any results as load workup takes place.